1. Field of the Invention
The present general inventive concept relates to a broadcast signal-receiving apparatus and a method of filtering noise signals. More particularly, the present general inventive concept relates to a broadcast signal-receiving apparatus and a method of filtering noise signals introduced by analog and/or digital broadcast signals that are adjacent to a selected digital broadcast signal received on a channel selected for viewing.
2. Description of the Related Art
Digital TV systems can compress, digitally convert, and transmit video and audio signals. Advancements in digital signal processes and communication technologies have lead to the development of a broadcast signal-receiving apparatus capable of receiving digital broadcast signals of an ATSC (Advanced Television System Committee) standard VSB (Vestigial Side Band) system out of digital broadcast signals, together with a NTSC (National Television System Committee) standard analog broadcast signals. These digital and analog broadcasts use the same RF channel bandwidth of 6 MHz such that the broadcast signal-receiving apparatus can use the same antenna and tuner to receive both analog and digital broadcast signals. Thus, analog and/or digital broadcast signals that are adjacent to a selected digital broadcast signal received on a channel selected for viewing occasionally interfere with each other and turn into noise signals.
FIG. 1 illustrates noise signals remaining when adjacent signals are filtered by a conventional broadcast signal receiving apparatus. As illustrated in FIG. 1, a SAW (surface acoustic wave) filter 40 filters a selected digital broadcast signal 10 received on a channel selected for viewing and an adjacent signal 20. A part of the adjacent signal 20 contained in a bandwidth of the SAW filter 40 is not filtered out, but is output together with the selected digital broadcast signal 10 as a noise signal 30. The noise signal 30 is processed together with the selected digital broadcast signal 10 and causes a degradation in quality of video and audio output signals.
The adjacent signal 20 is an analog or a digital broadcast signal that is adjacent to the selected digital broadcast signal 10 received on a channel selected for viewing. When digital and analog broadcasts are simultaneous, an NTSC standard analog broadcast signal is transmitted at a channel frequency adjacent to or identical to the selected digital broadcast signal 10. As a result, serious channel interferences can occur in the selected digital broadcast signal 10, thereby deteriorating signal-receiving characteristics of the broadcast signal-receiving apparatus.